Scuba divers typically use a conventional aluminum or steel compressed air breathing tank (scuba tank) strapped on the diver's body with the tank located on the diver's back. Such scuba diving tanks are well known and available commercially.
Scuba divers generally prefer to swim under water at an optimum swimming attitude where the diver's body is generally horizontal. The air tank strapped to the diver's back initially will be in a position generally parallel relative to the diver's desired horizontal body orientation as schematically shown, for example, in FIG. 1A. However, as the scuba diver swims underwater over a period of time, air in the tank is consumed and results in the tank becoming more buoyant and assuming a less than optimum attitude relative to the diver's body as schematically shown, for example, in FIG. 1B. In particular, the end of the air tank remote from the diver's head typically will rise relative to the diver's body as a result of consumption of air. The increased buoyancy of the air tank tends to buoy the diver's body toward an inclined angle as also schematically shown in FIG. 1B. The diver then must exert extra effort in order to try to maintain the optimum horizontal swimming attitude under water.
Diving equipment manufacturers have attempted to address this problem of increased tank buoyancy over diving time and resultant loss of optimum diver's swimming attitude by adding ballast weight to the tank. However, ballast weight has been added to the tank outer diameter at locations where the diver cannot readily eject the ballast in an emergency situation when the diver needs to surface rapidly and/or where the ballast positioned at a location relative to the tank that is less than effective at overcoming the problem of tank buoyancy, requiring increased ballast weight in order to address the tank buoyancy problem.
It is an object of the present invention to provide an underwater breathing tank with a buoyancy compensator that overcomes the aforementioned problem of tank buoyancy in a manner that permits the diver to readily jettison or eject ballast weight in a situation when the diver needs to surface rapidly.
It is another object of the present invention to provide an underwater breathing tank with a buoyancy compensator that overcomes the aforementioned problem of tank buoyancy by providing ballast weight at a location on the tank that improves the effect of the ballast weight.